3D carbonized orange peel: A self-floating solar absorber for efficient water evaporation

Interfacial solar steam generation (ISSG) is a sustainable and promising technology. Solar energy is used to desalinate seawater and purify industrial wastewater. Solar absorbers based on carbonized biowaste have received increasing attention because they are biocompatible, carbon-rich, hydrophilic, have low thermal conductivity, and exhibit excellent solar absorption. We fabricated a three-dimensional (3D) photothermal material based on carbonized orange peel (COP) for ISSG. The microscopic pores of COP ensured excellent thermal insulation, and the upward-concave shape enhanced light absorption and the self-floating capacity. COP exhibited an evaporation rate of 1.86 kg m⁻² h⁻¹ and energy efficiency of 87.90 % under 1 sun irradiation. Additionally, the salt rejection rate was 99.99 % during desalination, and the dye removal rate was 100 % during water purification. Our solar evaporator is thus a low-cost and efficient means of ISSG, and it shows that biowastes can serve as effective photothermal materials.